1. Field of the Invention
The invention relates to an apparatus for the heat treatment of at least one essentially cuboidal magazine for lead frames, which are parallel to a horizontal longitudinal direction of the magazine and are fitted with electronic chips, in at least one box which has a housing with a charging opening which is defined by end edges and can be closed by a door, and in which box at least one fan is arranged for subjecting the lead frames in the magazine to a hot gas.
2. Discussion of the Prior Art
Competitiveness in the mass production of semiconductors is nowadays in particular a question of the yield of qualitatively satisfactory components. The corresponding production batches must be made ready without a significant increase in costs and without an extended delivery time. This challenge calls for the use of processes and installations of very high reliability and productivity, it also being required that the smallest batch sizes can be processed without profitability being adversely affected by the batch size. For this purpose, various line concepts have been developed in order to feed lead frames arranged in magazines and fitted with electronic chips to individual wiring stations (so-called wire bonders). The lead frames are in this case passed from work station to work station.
One of these work stations comprises a curing installation, in which a so-called curing takes place, i.e. a hardening by polymerization of the epoxy resins, and here, in particular, of the adhesives which are used for fastening the electronic chips onto the lead frames.
For this purpose, until now a plurality of magazines with lead frames have been brought into a corresponding oven and subjected to hot gas (air or inert gas). This random heat treatment has considerable disadvantages, however, with respect to the curing process, the temperature profile, the stressing of the electronic components and the accompanying contamination of the components, of the lead frames and of the environment.
The object of the present invention is to provide a curing installation in which the abovementioned disadvantages do not occur, by the corresponding lead frames being treated in a specific and controlled manner such that uniform curing over the entire length of the lead frame takes place, and the electronic chips present on it are subjected to as little stressing as possible, keeping their contamination and the polluting of the environment to a minimum.
This object is achieved by the fan being supported on the housing and arranged therein in such a way that it generates in the region of the magazine at least one essentially horizontally directed gas stream which is essentially parallel to the longitudinal direction of the magazine, in order that the gas flows through the magazine.
As a result, the heat transfer between the gas and the electronic chips on the lead frames in the magazine is subsfantially increased, and consequently, the period of time which is required for heating up or cooling the electronic chips on the lead frames in the magazine is subsfantially reduced. Thus, the very temperature-sensitive electronic component parts of the electronic chips are subjected as little as possible and at the same time uniformly, to high temperatures. It is optimal to subject the chips to high temperatures only for as long as is necessary, in order, for example, to cure resins contained therein or, in general, to allow the desired chemical reactions to proceed therein.
Although the expectations with respect to the temperature consfancy in the magazine are already met in this exemplary embodiment, the time up until the electronic components on the gas outlet side of the magazine have virtually the same temperature as on the gas inlet side can be shortened still further.